1. FIELD OF THE INVENTION:
The present invention relates to a method of feeding a material to a hot forging machine and, more particularly, to a method of uncoiling a coiled material, straightening the uncoiled material, heating the straightened material, cutting the heated material and then feeding the cut material into a hot forging machine.
2. DESCRIPTION OF THE PRIOR ART:
Hitherto, the production of nuts or similar products from a wire or strip employs the steps of heating an elongated straight rod material in a heating furnace, intermittently extracting the heated elongated rod material from the heating furnace, cutting the extracted elongated rod material into pieces from the leading end of the material, and then forging the pieces of the material into the final shape and size. In this method, since the blank material is an elongated straight rod material there is a practical limit in the length of the material. Usually, therefore, elongated rod materials are jointed successively, so that a considerably long portions around the joint portions have to be wasted uneconomically. To obviate this problem, it has been proposed an apparatus which is adapted to uncoil a material which has been coiled as in the case of cold forging, straightening the uncoiled material, heating the straightened material and then feeding the heated material into the hot forging machine.
A typical example of such an apparatus includes a pair of cams fixed to a shaft drivingly connected to a main driving crankshaft of a hot forging machine. One of these cams is adapted to cause, through a connecting link and lever mechanism and a transmission rod, a reciprocatory rotary motion of a feed roller which is disposed on the inlet side of the heating device, while the other cam is adapted to upwardly shift an upper guide roller and the material during the backward rotation of the feed roller. In the forward rotation of the feed roller, the upper guide roller is lowered into cooperation with the feed roller, thereby intermittently feeding the material into the forging press. This apparatus is shown in Japanese Patent Unexamined Publication No. 38632/83.
This type of apparatus, however, cannot be used suitably for materials having large diameters, although it is practically usable for materials of comparatively small diameters. Namely, when the material has a large diameter, it is necessary to employ a straightening device having a multiplicity of stages. The driving power for driving the feed roll also has to be large, theoretically requiring an impractically huge lever and link mechanism. It is impossible to connect the lever and link mechanism to the conventional hot forging machine which is designed to handle the material in the form of an elongated straight rod, because such a hot forging machine is not designed to provide the shaft drivingly connected to the main crankshaft. In addition, there is a risk that the straightened material is undesirably bent when it is shifted upward during backward rotation of the feed roll.
Furthermore, the precision of operation is naturally limited due to the use of the cams, links and levers, and the use of a stopper for ensuring the precision is indispensable. Thus, the above-described known apparatus necessitates adjustment of the stopper and links for the purpose of control of the length at which the material is cut, and suffers from an inferior response characteristics.